This invention relates generally to a power transfer mechanism. More particularly it relates to a planetary gear assembly which may be shifted manually between a neutral position, a high range position wherein direct drive is established, and a low range position wherein reduction ratio drive is established.
In recent years there have been many improvements in drive trains, including improvements related to planetary gearing for establishing paths for the transfer of power. Some such planetary gear sets are shifted by engaging and disengaging friction elements manually, hydraulically, electrically or by some other suitable means. Other planetary gear sets are shifted by engaging and disengaging clutches. Normally this is done by sliding sleeves into and out of dental engagement with various elements for establishing high and low range modes. This requires considerable space and a large number of parts within the assembly. It has an important disadvantage in that more than one mesh point may be required for shifting. Further, in these arrangements the system is generally loaded when running in the locked up condition, causing vibration and excessive wear.
There remains a need for a planetary gear assembly which may be shifted simply between the various operating positions, which incorporates a minimum of parts and a minimum of mesh points, and which is not loaded when running locked up. There is a further need for such an assembly which is susceptible of economical manufacture and efficient operation.